Conventionally known rolling bearing devices for road-wheels on which road wheels of automotive vehicles or the like are mounted include one which has an inner shaft that is provided with, on its outer-side end, a flange on which the road wheel is mounted; and has an outer ring disposed around the inner shaft. The outer ring is fixed to a member of a vehicle body, whereby the rolling bearing device is assembled in the vehicle body.
By the way, the completed rolling bearing devices may be stored in warehouses, put in the stage of distribution or assembled in final products to be introduced on the market. If, in such cases, inspections or replacements of the rolling bearing device are necessary for various reasons, it is crucial to confirm the manufacturing attribute of the rolling bearing device in question, or to confirm the serial number or lot number, and the numerical quantity thereof.
In this connection, characters representing the date of manufacture and the like of the rolling bearing device may be die-stamped on a part of the surface thereof, thus offering information on the manufacturing attribute of the rolling bearing device. A rolling bearing wherein the characters for the identification of the manufacturing attribute thereof are represented on a bearing surface by die-stamping may be exemplified by one disclosed in Japanese Unexamined Patent Publication No. 2003-222146 (FIG. 1).
On the other hand, a vehicular hub unit may be constituted by a rolling bearing device including: a hub wheel (inner shaft) as a shaft body to which a road wheel, a disc rotor of a disc brake gear and the like are mounted; and a rolling bearing mounted on an outer periphery of the hub wheel for supporting the hub wheel. As disclosed in Japanese Unexamined Patent Publication No. 2001-162338, for example, such a rolling bearing device is constituted as follows. A cylindrical end of the above-mentioned hub wheel is radially outwardly bent and deformed, so as to be caulk-fixed to an axial end face of an inner ring of the above-mentioned bearing, whereby the end face of the inner ring is axially pressed for preventing the bearing from disengaging from the hub wheel.
Specifically, as shown in FIG. 9, the conventional rolling bearing device of this type includes: an outer ring member 101 which has a pair of outer raceways 101a, 101b and is fixed to the vehicle body side; a hub wheel 102 which includes an inner raceway 102a opposing the outer raceway 101a and allows the road wheel to be mounted to a vehicular-outer-side end thereof; an inner ring member 103 which is fitted on a vehicular-inner-side end of the hub wheel 102 and on which an inner raceway 103a opposing the outer raceway 101b is formed; and rolling elements 104, 105 which are constituted by balls rollably interposed between a respective pair of outer raceways 101a, 101b and inner raceways 102a, 102b in an opposing relation.
The inner ring member 103 is prevented from disengaging from the hub wheel 102 by means of a caulked portion 102b formed by bending and deforming a cylindrical end of the hub wheel 102 in a radially outward direction.
In the conventional rolling bearing device, a cover 106 is pressed into an inner periphery of a vehicular-inner-side of the outer ring member 101 in order to increase muddy water resistance. A vehicular-inner-side opening of the bearing device is sealed by the cover 106. On the other hand, a vehicular-outer-side opening of the bearing device is sealed by a seal member 107 interposed between the outer ring member 101 and the hub wheel 102.